If you're running an Eberron campaign, this is required reading. Keith Baker (The author) created the Eberron setting, but due to WotC technically owning the Eberron IP, everything has to go through their approval process. Thus, with every edition of D&D, the core Eberron book must spend the majority of it's pages re-explaining the basic setting, with little space to go in depth. So what we have here is an extremely talented writer with decades of pent up lore, finally allowed to put unrestricted pen to paper.

15 pages on the dwarves. Eberron: Rising from the Last War had 2.

62 pages on the 13 planes of existence. RftLW had 5.

Did you know there is an entire civilization beneath The thunder sea? Because I sure didn't. Here, have 16 pages on an entire underwater city that RftLW didn't mention (To my recollection).

You want new character archetypes? Check.

You want new racial feats? Check.

You want new character races? Check.

New magic items? New Monster stat blocks? Artillery used in the last war? Check. Check. Check.

How about everything above but it's also balanced as well as any official material, plus written by the actual dude that created the setting? Giant checkmark with a smileyface next to it.

This is the DMsGuild at its very best. Support the authors, get the hardcover version if you can possibly afford it, it's gorgeous, plus the PDF for that sweet CTRL-F power. As far as I'm concerned, this is core material.